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Tuesday, April 21, 2015

Product Focus: Biotium CF Dyes™ Range

CF™ dyes are a series of highly water-soluble fluorescent dyes
spanning the visible and near-infrared (NIR) spectrum for labeling
biomolecules, especially proteins and nucleic acids. Developed by
scientists at Biotium using new breakthrough chemistries, CF™ dyes rival or exceed the quality of other commercial dyes, such as Alexa Fluor® dyes, due to the following novel features.

Rhodamine dyes are known for their excellent photostability and good
fluorescence quantum yield; consequently several of the Alexa Fluor® dyes bear the rhodamine core structure.

Unfortunately, traditional rhodamine chemistry makes it difficult to
extend the fluorescence wavelength to the far-red region and even more
challenging in the near-IR region, especially for water-soluble dyes for
bioconjugation. Recently, Biotium scientists discovered a new way to
prepare novel rhodamine dyes of any fluorescence color from green to
near-IR.

The new chemistry is a key element in the development of many of our CF™ dyes, particularly our far-red CF™ dyes, which are not only bright and water-soluble but also extremely photostable.

Excellent labeling efficiency

Reactive dyes for bioconjugation are generally susceptible to
hydrolysis, which can cause problems for shipping, handling and storage
and result in lower labeling efficiency. Heavily sulfonated dyes, such
as the Alexa Fluor® dyes, DyLight® dyes and IRDye® are particularly hygroscopic, worsening the hydrolysis problem.

For example, the percent of active Alexa Fluor® 488 succinimidyl
ester (SE) could be well below 50% by the time of application (Alexa
Fluor 488 microscale labeling kit product information sheet,
Invitrogen). In contrast, all of Biotium’s amine-reactive CF™ dyes have a
relatively stable form of SE, which is more resistant to hydrolysis
than the SE in many of the Alexa Fluor dyes. Accordingly, CF™ dye SE products generally give consistently higher labeling efficiency, thus providing users a better value.

Near-IR dyes are typically much larger in size than dyes in the
visible range. The large size often results in serious problems of low
dye solubility, dye aggregation and poor fluorescence quantum yield. To
overcome the problems, many commercial near-IR dyes, such as the near-IR
Alexa Fluor® dyes, DyLight® dyes and IRDyes®, are prepared by placing a
number of negatively charged sulfonate group on the dyes. While
sulfonation improves dye solubility and fluorescence quantum yield to
some degree, it creates another even more serious problem: non-specific
binding of the bioconjugates prepared from the dyes.

For example, conjugation to a highly negatively charged dye can
dramatically alter an antibody’s isoelectric point (iP), which is
essential for maintaining specific antibody-antigen interaction. With
this insight, Biotium scientists devised a revolutionary new approach to
near-IR dye design that results in superior physical properties of the
dyes without introducing an excessive amount of negative charge.

Biotium’s near-IR CF™ dyes are based on the core structure of either
cyanine dyes or rhodamine dyes. Those core structures are modified such
that the intramolecular mobility of the dyes is restricted, which leads
to higher quantum yield and better water solubility without adding
excessive charge. As a result, near-IR CF™ dyes are much brighter and
more photostable than any other near-IR dyes. Most importantly,
antibodies labeled with near-IR CF dyes™ give far better signal-to-noise
ratio in immunostaining compared with antibody conjugates prepared with
other commercial near-IR dyes.

Stratech Scientific
is a distributor of high quality, competitively priced, reliable
products for research laboratories throughout the UK and Europe. Please
contact us to find out which ranges we can supply in your country.